All of the cards are gone. I'm in the first game where Lore plays a part - Wizards & Lore - and couldn't find anything in the rules regarding this. Should the discarded Lore cards be reshuffled and played again? Or is that it for the wizards' abilities? Just wanted some different opinions....

The lore cards are shuffled when the "Battlelore" command card is played.

However, I don't know what happens if you exhaust the lore cards without the "Battlelore" card being played. If it happened in one of my games, barring an official ruling otherwise, I would shuffle the discarded lore cards anyway.